1. Field of the Invention
The present invention relates to a bag supplying device that supplies packaging bags to an automated packaging machine.
2. Prior Art
Japanese Patent Application Publication (Kokoku) No. H07-5125 discloses a device that supplies packaging bags to an automated packaging machine.
In this bag supplying device, the bag surface of an uppermost empty bag of empty bags stacked horizontally in a bag storage receptacle is suction-chucked and lifted by a vacuum suction lifting device. The bag mouth of this empty bag is then gripped by a pair of bag gripping means provided near the tip end of a gripping portion main body (and transferred to the gripping means from the vacuum suction lifting device). The bag is next conveyed obliquely upward in a substantially rectilinear manner while being gradually changed to a vertical attitude. The bag is then moved more or less horizontally in this attitude and is placed in the position of the gripper of a packaging machine. The gripper is next closed and grips the empty bag, and then the gripping means are opened.
Japanese Patent Application Publication (Kokoku) No. 6-55604 also discloses a bag supplying device.
In this bag supplying device, the bag surface of the uppermost empty bag of empty bags stacked horizontally in a case is suction-chucked and lifted by the first suction chucking plate and suction plate that are provided at the tip end of a first swinging suction-chucking arm. The bag surface near the bag mouth is suction-chucked by the second suction chucking plate and suction plate that are provided at the tip end of a second swinging suction-chucking arm (that is, the bag is transferred from the fist suction chucking plate and suction plate to the second suction chucking plate and suction plate). Then, the bag is conveyed upward along a circular-arc-form track. The bag that takes a vertical attitude at the top is clamped at its mouth by a pair of clamping elements (that is, the bag is transferred from the second suction chucking plate and suction plate to a pair of clamping elements). The pair of clamping elements are then moved horizontally so that the empty bag is placed in the position of the gripper of a packaging machine. The gripper is closed and grips the empty bag, after which the pair of clamping elements 42 and 43 are opened.
In recent years, due to the problems of conservation of resources and waste treatment, etc., packaging bags with a small thickness have begun to be used. Furthermore, there has been a demand for an increased speed in the bag supplying process (i.e., an increase in the number of bags supplied per unit time) in order to increase the operation speed of the packaging machine.
However, in the device described in Japanese Patent Application Publication (Kokoku) No. H07-5125, the bags are shifted from a substantially horizontal attitude to a substantially vertical attitude during the rectilinear transfer to the gripper; as a result, the bags are easily affected by air resistance. Furthermore, as the thickness of the bags is reduced, the strength of the bags becomes weaker; and as the speed of the bag supply operation is increased, the bags are affected by a greater air resistance. As a result, problems arise. The bag surfaces would be warped by air resistance during transfer, so that the vertical attitude of the bags is lost, resulting in that the gripper cannot receive the bags in a stable fashion. Furthermore, in the above bag supplying device, the opening and closing of the gripping means that grips the bags is accomplished by an air cylinder; accordingly, the response characteristics are poor. Thus, this bag supplying device is not suitable for high-speed operation.
In the bag supplying device described in Japanese Patent Application Publication (Kokoku) No. H06-55605, the bags are rotated and conveyed via a circular-arc-form path that is oriented more or less along the bag surfaces and then take a vertical attitude. Subsequently, the bags in a vertical attitude are horizontally transferred over a short distance. Thus, this device is advantageous in that the bag surfaces are relatively less affected by air resistance. However, the bags are transferred twice during the conveying process. Accordingly, there is a greater possibility of transfer errors. Moreover, the time loss caused by the two-time transfer can easily increases, and it is difficult to achieve high-speed bag supply. In addition, since rotating-conveyance is performed by way of vacuum-chucking only one surface of each bag, there is a possibility that the bag mouth would open during the conveying process, especially when the speed is high. Thus, errors can easily occur in the transfer of the bags to the pair of clamping elements.
Accordingly, the present invention is to solve the problems with the conventional bag supplying devices.
It is thus an object of the present invention to provide a bag supplying device that eliminates transfer errors during the conveyance of bags.
It is another object of the present invention to provide a bag supplying device that supplies bags in a vertical attitude to a gripper, etc. of an automated packaging machine without causing any transfer errors of bags to the gripper, etc.
It is still another object of the present invention to provide a bag supplying device that can meet the decrease in the thickness of bags and the increase in the speed of bag supply.
The above objects are accomplished by a unique structure for a bag supplying device that is used in an automated packaging machine, and the bag supplying device comprises:
a conveying arm having a pair of clamping elements in the vicinity of a tip end thereof, the clamping elements for clamping bag mouths of empty bags,
a back-and-forth rotation means that causes the conveying arm to make a back-and-forth rotational movement about an axis of a horizontal rotational shaft, the back-and-forth rotational movement being made together with the rotational shaft so that the conveying arm rotates between a downwardly-oriented clamping position and a substantially horizontal intermediate position,
a reciprocating movement means that causes the conveying arm to advance and retract horizontally between the intermediate position and a transfer position, and
an opening-and-closing means that opens and closes the pair of clamping elements, wherein
when the conveying arm is in the clamping position, the clamping elements close and clamp a bag mouth of an empty bag,
the empty bag takes a substantially vertical attitude as the conveying arm rotates upward and approaches the intermediate position, and
the clamping elements open when the conveying arm advances and reaches the transfer position, so that the empty bag that is in a substantially vertical attitude is transferred to a next holding means.
The above objects are accomplished by another unique structure for a bag supplying device used in an automated packaging machine, and the bag supplying device comprises:
a conveying arm having a pair of clamping elements in the vicinity of a tip end thereof, the clamping elements for clamping bag mouths of empty bags,
a back-and-forth rotation means that causes the conveying arm to make a back-and-forth rotational movement about an axis of a horizontal rotational shaft, the back-and-forth rotational movement being made together with the rotational shaft so that the conveying arm rotates between a downwardly-oriented clamping position and a substantially horizontal intermediate position,
a slide frame that rotatably supports the rotational shaft,
a reciprocating movement means that causes the slide frame to make a reciprocating movement in a horizontal direction, thus causing the conveying arm to advance toward and retract from a transfer position, and
an opening-and-closing means that opens and closes the pair of clamping elements, wherein
when the conveying arm is in the clamping position, the clamping elements close and clamp a bag mouth of an empty bag,
the empty bag takes a substantially vertical attitude as the conveying arm rotates upward and approaches the intermediate position, and
the clamping elements open when the conveying arm advances and reaches the transfer position, so that the empty bag that is in a substantially vertical attitude is transferred to a next holding means.
Needless to say, when the slide frame makes the reciprocating movement, the conveying arm makes a reciprocating movement accordingly.
In the above bag supplying device: the opening-and-closing means that opens and closes the clamping elements is provided with a mechanical cam and a transmission mechanism. The mechanical cam is disposed outside the slide frame, and the transmission mechanism transmits a driving force from the mechanical cam to the clamping elements. The transmission mechanism comprises a first transmission rod and a second transmission rod, the first transmission rod being disposed along the horizontal rotational shaft and making a reciprocating movement together with the horizontal rotational shaft, and the second transmission rod being disposed along the conveying arm and rotates together with the conveying arm. The driving force of the mechanical cam is transmitted to the clamping elements via the first and second transmission rods.
Furthermore, between the mechanical cam and the first transmission rod, between the first transmission rod and the second transmission rod, and between the second transmission rod and the clamping elements, transmission mechanisms such as link mechanisms, levers, rods, etc., which transmit the driving force, are respectively interposed. In this case, the driving force of the mechanical cam opens and closes the clamping elements via a mechanical transmission mechanism. Thus, the response characteristics are improved compared the conventional air cylinder driving.
In the above structure, it is preferable that the horizontal rotational shaft has a hollow tubular form, and the first transmission rod is disposed in coaxial with and inside the hollow horizontal rotational shaft. Because of this structure, the position of the first transmission rod relative to the horizontal rotational shaft does not change even when the horizontal rotational shaft rotates. Thus, the driving force transmission mechanisms (between the mechanical cam and the first transmission rod, and between the first transmission rod and the second transmission rod) can be simplified. By way of causing the first transmission rod to advance and retract in, for instance, the axial direction or to rotate about its axis, the driving force from the mechanical cam is transmitted to the second transmission rod.
Furthermore, the above objects are accomplished by still another unique structure for a bag supplying device that is used in an automated packaging machine, in which the bag supplying device uses a vacuum suction holder instead of the pair of clamping elements. More specifically the bag supplying device having still another unique structure comprises:
a conveying arm having a vacuum suction holder in the vicinity of a tip end thereof, the vacuum suction holder for suction-chucking empty bags,
a back-and-forth rotation means that causes the conveying arm to make a back-and-forth rotational movement about an axis of a horizontal rotational shaft together with the horizontal rotational shaft so that the conveying arm rotates between a downwardly-oriented suction-chucking position and a substantially horizontal intermediate position, and
a reciprocating movement means that causes the conveying arm to advance and retract horizontally between the intermediate position and a transfer position, wherein
when the conveying arm is in the suction-chucking position, the vacuum suction holder suction-chucks an empty bag,
the empty bag takes a substantially vertical attitude as the conveying arm rotates upward and approaches the intermediate position, and
the vacuum suction holder stops suction-chucking when the conveying arm advances and reaches the transfer position, so that the empty bag that is in a substantially vertical attitude is transferred to a next holding means.
In addition, the above objects are accomplished by still a further unique structure for a bag supplying device that is used in an automated packaging machine, in which the bag supplying device uses a vacuum suction holder instead of the pair of clamping elements. More specifically the bag supplying device that has a further unique structure comprises:
a conveying arm having a vacuum suction holder in the vicinity of a tip end thereof, the vacuum suction holder for suction-chucking empty bags,
a back-and-forth rotation means that causes the conveying arm to make a back-and-forth rotational movement about an axis of a horizontal rotational shaft together with the horizontal rotational shaft so that the conveying arm rotates between a downwardly-oriented suction-chucking position and a substantially horizontal intermediate position, and
a slide frame that rotatably supports the horizontal rotational shaft, and
a reciprocating movement means that causes the slide frame to make a reciprocating movement in a horizontal direction, thus causing the conveying arm to advance toward and retract from a transfer position, wherein
when the conveying arm is in the suction-chucking position, the vacuum suction holder suction-chucks an empty bag,
the empty bag takes a substantially vertical attitude as the conveying arm rotates upward and approaches the intermediate position, and
the vacuum suction holder stops suction-chucking when the conveying arm advances and reaches the transfer position, so that the empty bag that is in a substantially vertical attitude is transferred to a next holding means.
Each of the above-described transfer devices of the present invention transfers empty bags to, for example, the gripper of an automated packaging machine. However, as long as the element that hold empty bags holds the bags in a substantially vertical attitude, then such an element is not limited to a gripper.